1. Field of the Invention
The present invention relates to an optical element and an optical apparatus.
2. Description of the Related Art
Japanese Patent No. 3573575 provides a radial gradient-index lens having a refractive index distribution in a radial direction of an optical axis in a medium so as to provide an optical system in which chromatic aberration for light including the g-line is well corrected. When a radial gradient-index lens has an inclination of a distribution that is different for each wavelength, a difference of a partial dispersion ratio between an effective diameter and the optical axis is set to a value within a predetermined range.
Japanese Patent No. 3573575 corrects the single lens's own chromatic aberration by providing a refractive index distribution, but does not provide a structure configured to well correct the chromatic aberration that occurs in an optical system including a plurality of dioptric optical elements.